ALO's Josh just responded back to me with this:
"If you are not planning on using the portable capabilities of The Passport, The Gateway is really a great option and it sounds quite good. The Passport will sound better if you have noisy AC in your place, but if the AC is fairly clean you'll get a nice, quiet experience out of your Pan Am with The Gateway. I mainly use the Gateway as I use my Pan Am here at my desk and it works very well for me.
At this time we do not have a replacement program for The Passport, we haven't had any trouble with the batteries so far :)
Let me know if you have further questions, I'm happy to help."
Guess I'll go for the Passport since my house is a bit old and I'm sure AC source isn't clean. Or I'll get the Model Astro Pro 14400 mAh as twinster posted earlier.